On my 2008 RG I had a hard time finding it too. If you look at the front, facing the headlights , it is on the bottom of the downtube and at about the 5 o'clock position if you were to look down from above.
already have one and in fact it is all i have. Still huge pain with the fixed fairing and lowers in the way. It took an entire large tube of red tacky to fill the head tube. Bike is brand new (only 400 miles and I did not want to run it without a good greasing lol.
Filled mine up with a good quality high temp synthetic and never had it drip or run on the front fender, and it gets extremely hot here in Florida also.